Prescription refill models of medication taking behaviour

Abstract

Medication taking can be defined in terms of two separate and distinct behaviours; adherence and persistence. These behaviours represent the ways in which a patient may take a treatment correctly; namely, acting in accordance with the prescribed interval and dosage of the treatment (adherence) and continuing the treatment for the prescribed duration of time (persistence). Prescription refill records are an invaluable resource for the efficient and objective assessment of medication taking behaviours in large numbers of patients, over extended periods of time. They can provide otherwise unobtainable information about the pattern and timing of drug exposure and the determinants and consequences of non-adherence and non-persistence. The use and validity of prescription refill records for the measurement of adherence has however been the subject of a number of recent criticisms. The most significant of these is the contention that; while prescription refill records are suitable for the measurement of treatment duration (persistence) they are unsuitable for the measurement of treatment execution (adherence), because they are unable to provide an adequate distinction between non-adherent and non- persistent behaviours.